Surface Passivation of (100)-Oriented GaAs via Plasma Deposition of an Ultrathin S-Containing Polymer Film and Its Effect on Photoluminescence

Abstract

Ultrathin S-containing polymer films of about 5 nm in thickness were deposited on the HCl-etched (100)-oriented single-crystal GaAs substrates via RF plasma polymerization of bis(methylthio)methane (BMTM). The chemical composition and structure of the BMTM plasma-polymerized GaAs(100) surface (pp-BMTM-GaAs surface) were investigated by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF−SIMS), respectively. The XPS and ToF−SIMS results showed that the sulfur atoms from the plasma-polymerized BMTM (pp-BMTM) film were bonded to both the Ga and As atoms. The low-temperature photoluminescence efficiency of the so-passivated GaAs single crystal was increased by 2-fold. The growth of the oxide layer on the pp-BMTM-GaAs surface was effectively hindered for up to at least 2 months under the atmospheric conditions. The rate of surface oxidation was also reduced significantly in the presence of the pp-BMTM barrier when the HCl-etched GaAs(100) was exposed to water and H2O2 solution. The 180°-peel adhesion test results indicated that the pp-BMTM film adhered strongly to the GaAs(100) surface.

Covalent Attachment of TAT Peptides and Thiolated Alkyl Molecules on GaAs Surfaces

“…Examination of the same core-level spectra of Ga 3d and As 3d reveals the increased number of GaAs species on the cleaned substrate and on the surfaces functionalized with MHA and ODT. The predominant peak in the Ga 3d spectrum when the surface was functionalized with the peptide A molecule corresponds to Ga−S species at a binding energy of 20 eV . The broad S 2p spectrum indicates the presence of an As plasmon loss peak, Ga 3s, and a As−S species on the surface.…”

“…The predominant peak in the Ga 3d spectrum when the surface was functionalized with the peptide A molecule corresponds to Ga-S species at a binding energy of 20 eV. 19 The broad S 2p spectrum indicates the presence of an As plasmon loss peak, Ga 3s, and a As-S species on the surface. The binding energy of a covalent bond between the sulfur and the surface is expected to be between 161.5 and 162.5 eV.…”

Atomic spectrometry update. Atomic mass spectrometry

“…An example of refined speciation analysis was the detection of covalent bonds between (100)GaAs and an ultra-thin (5 nm) S-containing polymer layer deposited by rf plasma to passivate the surface of GaAs. 200 The simultaneous presence of signals from ions such as AsS 2 1 or GaS 1 and RS 1 (R ~organic chain) clearly pointed to the covalent binding of the sulfide functionality in the coating and the GaAs. The identification was confirmed with XPS data.…”

Liquid-Phase Monolayer Doping of InGaAs with Si-, S-, and Sn-Containing Organic Molecular Layers

“…Due to the challenging surface chemistry of InGaAs and other III–V materials, the application of MLD has been quite limited. There have been reports of direct bonding to oxide-free III–V surfaces using organic thiols, − and due to the simplicity of the procedure and availability of suitable commercial molecules, as well as the excellent oxidation resistance offered by III–V-thiol chemistry, this was one of the functionalization approaches used in this study. Solution-phase S doping of InGaAs has been relatively widely reported due to the simplicity of the procedure. − Ammonium sulfide is often used to remove the native oxides on InGaAs, but the process conveniently results in a S-terminated surface, allowing diffusion of S as a monolayer into the InGaAs surface via a rapid thermal anneal step.…”